How To Test The GM Ignition Control Module (1995-2005)

This is i of the easiest GM ignition command modules to examination. This article will take yous step by footstep through the whole process of diagnosing and troubleshooting a bad ignition control module and ignition coil.

The ignition command module (ICM) and ignition coil tests in this article assume that your vehicle is cranking just not starting due to a NO-SPARK status. If you're GM car or truck starts and runs, this commodity volition not aid y'all.

Now, if y'all need to test a misfire condition, or examination the spark plug wires, or distributor cap on this type of GM ignition system, click here: How To Exam A Misfire / No-Spark No-First Status GM 4.3L, 5.0L, 5.7L Distributor Ignition System (1996-2004).

Since so many things can crusade your vehicle to non start (like a bad fuel pump, etc.), the following tutorial may be of aid to you:

  • How To Troubleshoot A No Kickoff (GM 4.3L, 5.0L, 5.7L) (at: troubleshootmyvehicle.com).

NOTE: The following ignition organisation circuit diagram may exist of assistance: Ignition System Circuit Diagram (1996-1999 Chevy/GMC Pick Upwards And SUV).

At the stop of this tutorial I've included a list of other tutorials that volition aid you diagnose a cranks just does non get-go status (in case it's not ignition system related).

En Español You lot can discover this tutorial in Spanish here: Cómo Probar El Módulo De Encendido GM 4.3L, v.0L, v.7L (1995-2005) (at: autotecnico-online.com).

Symptoms Of A Bad Ignition Module And Ignition Coil

Generally, when the ICM or the ignition scroll fails, your GM car or truck will creepo merely not start. Specifically, the ignition curlicue will not spark.

For this particular reason (and before you lot follow the test procedures in this tutorial), you need to verify that the ignition coil IS NOT sparking past connecting a spark tester directly on the ignition coil'due south tower and cranking the engine.

This is a pretty easy examination, merely it must be washed with a spark tester. You can find the test steps hither: Test 4: Spark Examination At Ignition Coil Belfry (this exam belong to this tutorial: How To Exam A Misfire / No Spark-No First Condition (4.3L, five.0L, 5.7L 96-04)).

NOTE: When the ignition roll or the ICM start to neglect, they don't always cause a cranks but does NOT offset condition, since sometimes these components tin can fail intermittently. In this scenario, your vehicle will beginning and run most of the time, but every now and then it won't. If this is the case, you'll accept to wait till the car or truck does not start to use the tests in this article.

What Tools Practise I Demand?

Yous don't demand a whole lot of stuff, heck, you don't even need a scan tool (tho' a browse tool is of import to have, but not for this commodity)! Here is what you're gonna' need to finer utilise the information in this article:

  1. A multimeter (don't have a digital multimeter? Need to buy 1? Click here to run across my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing).
  2. An LED light. To meet a photo of this tool click hither: Abe's LED Lite.
  3. A 12 Volt test light.
  4. A helper to crank the engine.
  5. A wire piercing probe. This tool is a time saver. If you need to meet what this tool looks like, click here: Wire Piercing Probe.

Equally yous can see/read, these are simply basic tools, nix fancy, improvident or EXPENSIVE.

Basic Operating Theory

Here is a little background data to help yous diagnose the ignition command module (ICM) or the ignition curl. In a nutshell, when your turn the key and start cranking the engine:

  1. Power in the form of 12 Volts flows into the crankshaft position (CKP) sensor, the ignition control module (ICM), the ignition whorl, among several things.
  2. The crankshaft position (CKP) sensor starts to create its CKP signal, which information technology sends to the PCM.
    • The crankshaft position sensor is a Hall Consequence type sensor and produces a digital (ON/OFF) signal that can be seen with an LED or an oscilloscope. On an oscilloscope, information technology produces a digital foursquare waveform.
  3. The PCM, upon receiving the crank point (along with other sensor input signals) kickoff to exercise its petty song and dance and sends the ignition command module (ICM) a betoken called the IC signal (IC=Ignition Control).
  4. With this IC signal, the ignition module starts to activate the ignition coil to beginning sparking with a Switching signal.
    • Equally y'all're probably already aware, the Switching signal is but a term that describes the switching 'ON and OFF' of the Principal Current'south path to Footing (the Primary Current refers to the 12 Volts supplied to the ignition scroll).

If everything is working properly, the engine will outset. At present, the important thing to know is that the PCM controls the creation of spark from the commencement (crank up) and at all engine speeds thru' the ignition command module (ICM). The really cool matter about this type of ignition organisation is that all of these signals (IC indicate and the Switching signal) tin be tested easily with some very simple tools.

Where To Buy The ICM And Ignition Curlicue And Save

The following links will assist you lot comparison shop for the factory original ignition command module and ignition curlicue:

Not sure if the ignition organisation components above fit your item GM vehicle? Don't worry, once you lot get to the site, they'll make sure they fits and if they don't, they'll discover yous the right ones.

Ignition Control Module (ICM) Circuit Descriptions

Ignition Control Module (ICM) Circuit Descriptions. How To Test The GM Ignition Control Module (1995-2005)

The ignition control module (ICM) has 4 wires coming out of information technology. Below are the descriptions of what each circuit does. Each circuit is identified past a letter, and this is the same letter that y'all will find on the ignition module's connector.

  • Circuit labeled A -Pink Wire:
    • Ability (12 V) Excursion.
  • Circuit labeled B -White Wire:
    • Ignition Control (IC) Signal.
  • Circuit labeled C -Black with White stripe Wire:
    • Engine Ground Circuit.
  • Circuit labeled D -White with Blackness stripe Wire:
    • Switching Signal Circuit.

The following ignition arrangement excursion diagram may be of help: Ignition System Circuit Diagram (1996-1999 Chevy/GMC Pick Up And SUV).

Ignition Scroll Circuit Descriptions

Ignition Coil Circuit Descriptions. How To Test The GM Ignition Control Module (1995-2005)

The ignition coil on your automobile or truck may have or may not take 3 wires coming out of information technology. Whether information technology does or doesn't doesn't matter, the info in this test article nevertheless applies. Below are the descriptions of what each circuit does. Each circuit is identified past a letter, and this is the aforementioned letter that y'all volition find on the ignition coil'due south connector.

  • Circuit labeled A -Pinkish Wire:
    • Power (12 Five) Circuit.
  • Circuit labeled B -White Wire:
    • Tach Indicate for the tachometer in the musical instrument cluster if equipped.
  • Circuit labeled C -White with Black stripe Wire:
    • Switching Signal Circuit. This wire (circuit) comes from the ignition module.

The post-obit ignition organization circuit diagram may be of assist: Ignition System Circuit Diagram (1996-1999 Chevy/GMC Pick Upwards And SUV).

Ignition System Diagnostic Manual Download

If you'd like to have admission to a wiring diagram, ignition component connector pivot-outs, and the entire testing process in i place, then take a look at the following diagnostic manuals in downloadable PDF format:

Chevrolet/GMC C/Yard Series Full Size Selection Ups:

1996 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: iv.3L, 5.0L, 5.7L, vii.4L
1996 Full Size Option Upwardly
Ignition Organisation No-Start Diagnostic Manual

$3.99 USD

All of the information you lot need to diagnose a misfire or a no-get-go problem (caused past the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Firing orders.
  • Complete step-by-footstep testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996 Chevrolet C1500, C2500, C3500 Option Up.
  • 1996 Chevrolet K1500, K2500, K3500 Pick Up.
  • 1996 GMC C1500, C2500, C3500 Pick Up.
  • 1996 GMC K1500, K2500, K3500 Pick Up.
1997 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1997 Full Size Selection Up
Ignition Organization No-Start Diagnostic Manual

$3.99 USD

All of the information you need to diagnose a misfire or a no-first problem (acquired past the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Firing orders.
  • Consummate pace-by-stride testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1997 Chevrolet C1500, C2500, C3500 Pick Up.
  • 1997 Chevrolet K1500, K2500, K3500 Pick Upward.
  • 1997 GMC C1500, C2500, C3500 Option Upwards.
  • 1997 GMC K1500, K2500, K3500 Pick Upward.
1998 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, 5.0L, 5.7L, seven.4L
1998 Total Size Pick Up
Ignition Organization No-Start Diagnostic Manual

$3.99 USD

All of the information you demand to diagnose a misfire or a no-start problem (caused by the ignition whorl, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Firing orders.
  • Complete step-by-footstep testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 1998 Chevrolet C1500, C2500, C3500 Pick Up.
  • 1998 Chevrolet K1500, K2500, K3500 Selection Upwardly.
  • 1998 GMC C1500, C2500, C3500 Pick Up.
  • 1998 GMC K1500, K2500, K3500 Pick Up.
1999 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, 5.0L, 5.7L, seven.4L
1999 Full Size Choice Upward
Ignition Arrangement No-Kickoff Diagnostic Manual

$3.99 USD

All of the information you need to diagnose a misfire or a no-start problem (acquired by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1999 Chevrolet Silverado, C1500, C2500, C3500 Pick Upward.
  • 1999 Chevrolet K1500, K2500, K3500 Pick Up.
  • 1999 GMC Sierra, C1500, C2500, C3500 Pick Upwardly.
  • 1999 GMC K1500, K2500, K3500 Pick Up.
2000 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, five.7L, seven.4L
2000 Full Size Choice Up
Ignition Organisation No-Beginning Diagnostic Manual

$3.99 USD

All of the data y'all demand to diagnose a misfire or a no-starting time trouble (caused by the ignition roll, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 2000 Chevrolet Silverado, C2500, C3500 Choice Upwards.
  • 2000 Chevrolet K1500, K2500, K3500 Pick Up.
  • 2000 GMC Sierra, C2500, C3500 Pick Up.
  • 2000 GMC K1500, K2500, K3500 Pick Up.

Chevrolet Express Van and GMC Savana Van:

1996-1999 Chrevrolet Express/GMC Savana PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1996-1999 Express/Savana
Ignition System No-Start Diagnostic Manual

$iii.99 USD

All of the information you lot need to diagnose a misfire or a no-first problem (acquired by the ignition curl, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Ignition organization component part numbers.
  • Firing social club.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 1996-1999 Chevrolet Express Van.
  • 1996-1999 GMC Savana Van.
2000 Chrevrolet Express/GMC Savana PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
2000 Limited/Savana
Ignition Arrangement No-Start Diagnostic Manual

$iii.99 USD

All of the information yous need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition organisation component part numbers.
  • Firing society.
  • Complete step-by-pace testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 2000 Chevrolet Express Van.
  • 2000 GMC Savana Van.

Chevrolet Tahoe and GMC Yukon:

1996-2000 Chrevrolet Tahoe/GMC Yukon PDF
Engines: 5.7L
1996-2000 Tahoe/Yukon
Ignition Organisation No-Commencement Diagnostic Manual

$3.99 USD

All of the information y'all need to diagnose a misfire or a no-offset problem (acquired by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagram.
  • Component pin outs.
  • Connector pin outs.
  • Firing lodge.
  • Ignition system component part numbers.
  • Firing guild.
  • Complete step-past-footstep testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 1996-2000 Chevrolet Tahoe (4x2 and 4x4).
  • 1996-2000 GMC Yukon (4x2 and 4x4).

Chevrolet and GMC Suburban:

1996-1999 Chrevrolet/GMC Suburban PDF
Engines: v.7L, 7.4L
1996-1999 Suburban
Ignition System No-Starting time Diagnostic Manual

$3.99 USD

All of the information yous need to diagnose a misfire or a no-kickoff problem (caused past the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagram.
  • Component pivot outs.
  • Connector pivot outs.
  • Ignition organisation component office numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-1999 Chevrolet Suburban (4x2 and 4x4).
  • 1996-1999 GMC Suburban (4x2 and 4x4).